Sperm activity rate of 20.42% may be caused by long time no sex life, or it may be caused by varicocele, weak spermatozoa and other diseases. 1. Bad no sex life: If men do not have sex for a long time, it may cause high sperm density and poor mobility, thus making the sperm activity rate 20.42%. 2. Varicocele: Varicocele is a kind of vascular lesion, due to the incomplete development of venous valves can cause blood reflux, or congenital or acquired factors lead to proximal obstruction caused by the obstruction of reflux, will make the vein high pressure and hypoxia, so that there is a decrease in the sperm activity rate. 3. Weak spermatozoa: Weak spermatozoa generally refers to a condition in which less than 32% of the spermatozoa in the semen parameters are forward-moving, and the cause of the condition is mostly related to congenital factors, endocrine abnormalities, immunologic factors, and micronutrient deficiencies. There are many reasons for the 20.42% sperm motility, so we suggest that the patient should consult a doctor in time to clarify the cause of the disease and then standardize the treatment. Daily need to rest more, do not stay up late, and develop good habits. Quit smoking and drinking, exercise appropriately, and maintain a good mood.